如何按多个字段比较对象 [英] How to compare objects by multiple fields

问题描述

假设您有一些对象，它们具有多个字段，可以通过以下方式进行比较:

Assume you have some objects which have several fields they can be compared by:

public class Person {

    private String firstName;
    private String lastName;
    private String age;

    /* Constructors */

    /* Methods */

}

所以在这个例子中，当你问:

So in this example, when you ask if:

a.compareTo(b) > 0

您可能会问 a 的姓氏是否在 b 之前，或者 a 是否比 b 大，等等...

you might be asking if a's last name comes before b's, or if a is older than b, etc...

在不增加不必要的混乱或开销的情况下，在这些类型的对象之间启用多重比较的最简洁方法是什么?

What is the cleanest way to enable multiple comparison between these kinds of objects without adding unnecessary clutter or overhead?

• java.lang.Comparable 接口只允许通过一个字段进行比较
• 在我看来，添加大量比较方法(即 compareByFirstName()、compareByAge() 等...)很混乱.

• java.lang.Comparable interface allows comparison by one field only
• Adding numerous compare methods (i.e. compareByFirstName(), compareByAge(), etc...) is cluttered in my opinion.

那么最好的方法是什么?

So what is the best way to go about this?

推荐答案

您可以实现一个 Comparator 来比较两个 Person 对象，并且您可以检查尽可能多的你喜欢的字段.您可以在比较器中放入一个变量，告诉它要与哪个字段进行比较，尽管编写多个比较器可能会更简单.

You can implement a Comparator which compares two Person objects, and you can examine as many of the fields as you like. You can put in a variable in your comparator that tells it which field to compare to, although it would probably be simpler to just write multiple comparators.

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